I’ve received the Really Right Stuff L-bracket for the Sony A7 II. It fits the A7R II perfectly.
RRS tells me that an L-bracket coming for the Sony A7R II which will include a stabilizing screw for the “L” part against the strap lug (I’ve seen a prototype picture) for a rigid support; it’s a nice touch that I look forward to. ALSO, the RRS custom plate for the A7R II will have a full width base plate over the bottom of the camera.
I’ll be going with the A7R II plate when it arrives; I like the strap lug idea and I like the full base plate.
Side note: if the lens is heavy, the camera ought not to be used to support the lens anyway (use a tripod foot or other support to mount the rig in the head).
UPDATE Dec 2015: the Really Right Stuff BA7R2-L Set for Sony A7 II or A7R II is a form-fitting outstanding piece of engineering. It is extremely sturdy and well built, but does require installing by removing the battery cover door.
I elected to stick with the simpler BA72-L set for my A7R II, because it is smaller and lighter and can be quickly removed (in part, I needed to swap between cameras).